<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>作用域-面试题</title>
</head>
<body>
    
<script type="text/javascript">
    var x = 10
    function fn(){
        console.log(x)

    }
    function show(f){
        var x = 20
        f()
    }
    show(fn) // 10 
</script>
</body>
</html>